In Vivo Gene Therapy Delivery Procedure and Device

ABSTRACT

A “localizable” systemic gene therapy system is provided substantially increasing the transfection efficiency of the gene vectors into targeted tissue cells and substantially reducing the escape of the gene vectors from the targeted tissue volume, such as would waste the vectors, promote undesired immune reactions, and/or incur prohibitive costs for the required dose of gene-containing virus vectors. In this regard, the invention provides a means to simultaneously achieve local electroporation and gene-containing vector injection in a portion of a vascularized organ. It includes two double-balloon catheters that create contained volumes in parallel blood vessels for the introduction of vectors with reduced loss along with electrodes providing electroporation of the cells in the same location where the vectors are injected.

CROSS REFERENCE TO RELATED APPLICATION BACKGROUND OF THE INVENTION

The present invention relates to a method and apparatus for genetherapy, and more particularly, an improved gene therapy deliverysystem.

Genetic mutation based metabolic diseases significantly reduce qualityof life for hundreds of millions of people in the world and account for70% of child hospitalizations and 10% of adult hospitalizations. Thereare hundreds of such diseases, including diabetes, cystic fibrosis,sickle cell anemia, hemophilia, and thalassemia. Many of them involvethe liver due to its central role in metabolism.

Gene therapy has been found to be a promising cure for these diseases bytransducing functional genes (i.e, a functional portion of a DNAsequence) into a small portion of cells within the target organ, forexample, liver cells, thus correcting the inherited metabolicdiscrepancy. It has been found that only a small fraction of liver cells(hepatocytes) need to be converted, for example, about 5% in the liver,in order to produce therapeutic gene products sufficient to cure thedisease.

A carrier of gene, such as a viral vector, can be used to deliverforeign, functional genes into cells. By transferring the functionalgene into a virus that either enters the cell membrane throughendocytosis (viruses without a viral envelope) or binds to receptors onthe cell membrane and fuses with the cell membrane thus releasing thegenetic material (viruses with a viral envelope), genes can beintroduced into the cell. Depending on the virus used to deliver thegene, the viral genetic material either integrates into a chromosome ofthe cell or persists episomally without integration within the nucleusof the cell and expresses the introduced gene to treat the geneticdefect.

Systemic gene therapy, which delivers functional genes via thecirculatory system, has been found to be a successful delivery methodfor functional genes in small mammals (smaller than an average dog).However, this treatment has not been found to be scalable to largemammals for three reasons:

First, inefficient transduction of target cells necessitates large,cost-prohibitive gene vector doses. The larger size of the animal andmore extensive blood flow pathways necessitates much larger doses ofexpensive vectors in order to convert the necessary amount ofhepatocytes for effective therapy.

Second, the patient may have pre-existing antibodies that neutralize avirus capsid used as a gene vector rendering therapeutic attempt lesseffective or ineffective.

Third, systemic injection of such large quantities of the virus vectorcan trigger adaptive immunity that destroys not only the virus but alsothe genetically modified cells.

Compensating for these problems by introducing large amounts of vectoris impractical because of the high expense of producing the vector andthe inherent risks associated with injecting large amounts of virus intoa patient.

SUMMARY OF THE INVENTION

The present invention provides a “localizable” liver gene therapy systemsubstantially reducing the escape of the gene vectors from the liver,such that the waste of vector through systemic dilution is minimized,which would limit the undesired immune reactions. In this regard, theinvention describes a two inflatable balloon catheter that creates afinite contained volume along coextending blood vessels to increase thelocal concentration of virus for increased uptake of vectors in thenearby tissue with reduced vector loss. While the contained volumeswould seem to be counter to the intent of treating a large amount oftissue, electrodes in adjacent blood vessels are used to produceelectroporation in the tissue region between the electrodes offsettingthis localization of delivery and improving uptake of the vector.

Generally, a pair of catheters is inserted into a venous access site forhepatic vein catheterization. The medical professional may visualize thehepatic vein using ultrasound or x-ray (fluoroscopy) guidance to advancethe catheter into coextending blood vessels of the liver. A pair ofinflated balloons flanking an active delivery section of the cathetermay secure the location and positioning of the catheter's activedelivery section while also containing the vector volumes. Viral vectorsare then injected through the pair of catheters to pass outward throughholes in the active delivery section of the catheters to define a genedelivery area. An electrical charge is delivered to create a voltagebetween electrodes of the pair of catheters and an electric fieldcommensurate with the gene delivery area. This results in an improvedtransduction rate of the viral vectors into the hepatic cells andtherefore improved conversion of the hepatocytes with smaller vectordoses.

The present invention provides gene therapy delivery system including afirst balloon catheter providing a distal end having a first and secondinflatable balloon spaced apart along the distal end to define anintervening catheter section and at least one passageway through adelivery lumen of the intervening catheter section for the delivery of agene vector; a second balloon catheter providing a distal end having afirst and second inflatable balloon spaced apart along the distal end todefine an intervening catheter section and at least one passagewaythrough a delivery lumen of the intervening catheter section for thedelivery of a gene vector; a first electrode extending along the firstballoon catheter; a second electrode extending along the second ballooncatheter; and a power supply providing a voltage across the first andsecond balloon catheters.

It is thus a feature of at least one embodiment of the invention toreduce the cost-prohibitive gene vector doses for targeted highefficiency delivery by eliciting electroporation across a large area oftissue not just within the blood vessel.

The first and second electrode may extend within the delivery lumen ofthe first and second balloon catheter, respectively.

It is thus a feature of at least one embodiment of the invention toprevent electrical charge from passing through tissue or to expose bloodor tissue to conductive wires.

The first and second electrode may terminate before a distal tip of thefirst and second balloon catheters, respectively.

It is thus a feature of at least one embodiment of the invention toisolate the electric field to the intervening catheter section betweenthe two balloons.

The first and second electrode may extend substantially parallel with acatheter sidewall.

It is thus a feature of at least one embodiment of the invention to usewire electrodes that still provide clearance within the catheter lumenfor vector flow.

The first and second electrode may provide a coaxial conductor having aninner and outer coaxial conductive element and wherein the outerconductive element is removed from the coaxial conductor within theintervening catheter section to allow transmission of electrical fieldfor electroporation. A proximal end of the catheter may provide anelectrical connector providing separate connections to the inner andouter coaxial conductive elements. The inner conductive element may beany biocompatible conductive metal, such as, but not limited to,stainless steel.

It is thus a feature of at least one embodiment of the invention toisolate the electric field between the intervening catheter sections ofthe first and second catheters.

The first and second electrode may provide a coaxial conductor whereinthe coaxial conductor is insulated within the intervening cathetersection to prevent current flow to an exterior of the first and secondballoon catheters.

It is thus a feature of at least one embodiment of the invention toprotect the surrounding tissue from damage.

The intervening catheter section includes a plurality of perfusion holesspaced along the intervening catheter section. The intervening cathetersection may include at least one perfusion hole centered within theintervening catheter section.

It is thus a feature of at least one embodiment of the invention tooptimize delivery of the viral vector to a large tissue area surroundingthe blood vessel.

The catheter may have at least two lumens, one communicating with atleast one of the balloon catheters and the other communicating with thedelivery lumen. One of the first and second inflatable balloon may bepositioned at a distal tip of the first and second balloon catheters.

It is thus a feature of at least one embodiment of the invention toindependently inflate the balloons separate from the flow of vectorthrough the catheter for independent control.

The present invention also provides a method of gene therapy having thefollowing steps: providing a first balloon catheter providing a distalend having a first and second inflatable balloon spaced apart along thedistal end to define an intervening catheter section and at least onepassageway through a delivery lumen of the intervening catheter sectionfor the delivery of a gene vector, a first electrode extending along thefirst balloon catheter; providing a second balloon catheter providing adistal end having a first and second inflatable balloon spaced apartalong the distal end to define an intervening catheter section and atleast one passageway through a delivery lumen of the interveningcatheter section for the delivery of a gene vector, a second electrodeextending along the second balloon catheter; inserting the first ballooncatheter into a first blood vessel of a patient; inserting the secondballoon catheter into a second blood vessel of the patient; injecting agene vector through the delivery lumen of the intervening cathetersection to deliver the gene vector into surrounding cells; anddelivering an electrical charge to one of the first and secondelectrodes to produce a voltage across between the first and secondballoon catheter.

One of the first and second electrodes may be a return electrode. Thefirst and second electrical conductor electrodes may be separated by anaverage distance of 5-30 mm.

It is thus a feature of at least one embodiment of the invention toelectroporate a larger area of liver cells, coextensive with the tissuearea between electrodes for improved uptake of vector.

These particular objects and advantages may apply to only someembodiments falling within the claims and thus do not define the scopeof the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a human receiving intravenous gene deliverythrough catheterization of a hepatic vein of the liver through venousaccess sites of the body;

FIG. 2 is a perspective view through the liver of the human of FIG. 1after insertion of a pair of catheters in two separate hepatic veins ofthe liver;

FIG. 3 is a cross sectional view of one of the catheters of the presentinvention having an active delivery portion flanked by occlusionballoons and a conductor electrode extending through the lumen of thecatheter to effectuate an electric field with a second catheter;

FIG. 4 is an enlarged view of FIG. 2 showing the pair of cathetersinserted into the lower hepatic veins of the liver and providingdispersion of viral vectors from the catheters into a gene delivery areawhile an electric field is created around the catheters;

FIG. 5 is a chart showing a pattern of electrical field pulses deliveredto the conductor electrodes of the pair of catheter; and

FIG. 6 is a flow chart showing the method steps of gene therapyaccording to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1, a gene therapy delivery system 10 may includeat least two catheters 12, and preferably a pair of catheters 12 a, 12b, inserted within the body to deliver fluids containing genes to atarget organ of a human patient 14 for transduction into cells. Thefluids may be intravenously injected by a syringe 16 or a pump (notshown) into a proximal end 17 of the catheter 12 extending outside ofthe body and into a catheter insertion site. The fluids may includeviral vectors 18, for example, retroviruses, lentiviruses, adenoviruses,adeno-associated viruses, and the like containing functional genes forgene therapy.

While the present invention is illustrated as a gene therapy deliverysystem 10, it is understood that the delivery system 10 may also be usedto deliver drugs, for example, to a tissue or tumor site.

The catheter 12 may be inserted into a peripheral or central vein of thehuman patient 14 through a venous access site 20 allowing forcatheterization of a hepatic vein 22 of the liver 24 of the humanpatient 14, for example, at the antecubital vein 20 a, the jugular vein20 b, or the femoral vein 20 c. As illustrated, the catheter 12 may beinserted at an incision inside the neck of the human patient 14proximate to the jugular vein 20 b and then drawn downward through thehepatic vein 22 into the liver 24. The medical professional may use aguide wire (not shown) to facilitate placement of the catheter 12allowing the catheter 12 to be installed over the guide wire afterplacement of the guide wire. This catheterization process may also befacilitated by real-time visualization by a medical professional throughultrasound or x-ray (fluoroscopy) guidance.

Referring also to FIG. 3, each catheter 12 may include at least oneproximal port 30, for example, two proximal ports 30 connected by a Yconnector 32, allowing different fluids to be injected into the catheter12. The catheter 12 may also provide a separate balloon inflation port34 and balloon inflation tube 36 co-extending with and substantiallyparallel to the catheter 12 to provide inflation of one or more balloons38 of the catheter 12, as further described below. The balloon inflationport 34 may also include a valve controlling flow through the tube 36 toinflate or deflate the balloons 38 as desired.

While it is shown that the catheter 12 is installed into the hepaticvein 22 of the liver 24 of the human patient 14 for gene therapy, it isunderstood that the catheter 12 may also catheterize other organs ortissues of the human patient 14 such as the kidney or pancreas.

Referring now to FIG. 2, each catheter 12 may be fed by the medicalprofessional through the inferior vena cava 40 of the liver 24 and intoone of the upper hepatic veins 22 of the liver 24, for example, theright hepatic vein 22 a, left hepatic vein 22 b, or middle hepatic vein22 c. The catheter 12 may be further fed from the upper hepatic veins 22into coextending lower blood vessels 42 branching from the upper hepaticveins 22 and which contact with the hepatic tissue 44. For example, afirst catheter 12 a may be fed into one of the upper hepatic veins 22and terminate in a lower blood vessel 42 a while a second catheter 12 bis fed into the same upper hepatic vein 22 as the first catheter 12 abut terminate in a lower blood vessel 42 b sharing adjacent tissue withthe lower blood vessel 42 a. In this manner, the first catheter 12 a andsecond catheter 12 b are in relatively close proximity, about 5-30 mm,allowing an electric field 46 to be created between the first catheter12 a and the second catheter 12 b as further discussed below.

Referring now to FIG. 3, each catheter 12 may have a constructionfacilitating dispersion of the viral vector 18 through the catheter 12as well as electroporation of the hepatic cells 44 as described below.

The catheter 12 may include a thin, flexible tube having an outer wall50 made from a medical grade material such as vinyl, rubber latex, andsilicone. The outer wall 50 has sufficient flexibility to flex withflexure of the catheter 12 without holding a bent shape and withoutchanging the stiffness of the outer wall 50. The outer wall 50 may havean outer diameter of 1.5-3 mm and an inner dimeter of 0.8-2.5 mm. Thecatheter 12 may be consistent with a 5 French gauge catheter, 6 Frenchgauge catheter, 7 French gauge catheter, 8 French gauge catheter or 9French gauge catheter.

The outer wall 50 may provide an inner lumen 52 allowing for the flow offluids therethrough. For example, the internal lumen 52 may allow forthe passage of the viral vectors 18 from the proximal port 30 extendingoutside the body to a terminal end 54 of the catheter 12 positionedwithin the lower blood vessel 42. The terminal end 54 may be a straightend terminating at a rounded enclosed tip or catheter cap. The terminalend 54 may also support a balloon 38 as further described below.

When installed within the lower blood vessel 42, a distal end 56 of thecatheter 12 may provide an active section 60 delivering the viral vector18 through the outer wall 50 and into the lower blood vessel 42 andfurther flanked by spaced apart balloons 38, as further discussed below.The outer wall 50 of the catheter 12 may include one or more exit ports58 within the active section 60 of the catheter 12 allowing for theegress of viral vectors 18 injected into the catheter 12, flowingthrough the inner lumen 52, and flowing outward into the surroundinghepatic cells 44. The exit ports 58 may be approximately 0.1-0.4 mm indiameter or may be approximately ¼ to ½ of the inner diameter of thecatheter 12. It is understood that any number of exit ports 58 may beincluded within the catheter outer wall 50 depending on the desiredlength of the active section 60, and in any configuration around acircumference of the outer wall 50.

The exit ports 58 may be linearly aligned along a longitudinal axis 62of the catheter 12, or alternatively, the exit ports 58 may be staggeredin varying positions around a circumference of the outer wall 50 alongthe longitudinal axis 62 of the catheter 12. The exit ports 58 may besubstantially centered longitudinally within the active section 60. Forexample, a single exit port 58 may be centered within the active section60 or more than one exit ports 58 may be spaced symmetrically about thecenter the active section 60 along substantially the entire length ofthe active section 60.

Alternatively, the outer wall 50 may be a porous material having minuteopenings allowing the viral vectors 18 to permeate the outer wall 50 ofthe tube and disseminate into the surrounding hepatic cells 44.

Generally, it is understood that the active section 60 allows for theegress of the viral vectors 18 from the inner lumen 52 into the hepatictissue 44 surrounding the active section 60 of the catheter 12.

The dispersion of viral vectors 18 volumes may be contained by at leasttwo balloons 38, and preferably a pair of balloons 38 a, 38 b, spacedapart and flanking the active section 60 of the catheter 12 deliveringthe viral vector 18. A distal balloon 38 a may be positioned at or nearthe terminal end 54 of the catheter 12 and a proximal balloon 38 b maybe positioned upstream from the terminal end 54 on the proximal side ofthe active section 60.

The balloon 38 may be integrally molded with the catheter 12, forexample, built within or as part of the outer wall 50 of the catheter12, or may be bonded to the outer wall 50 of the catheter 12, forexample, by a curable adhesive sealing an outer perimeter of the balloon38 material to the outer wall 50 to create an airtight seal. The balloon38 may be made of a material which resiliently deforms under radialpressure, for example, polyethylene (PE), nylon, polyamide, polyetherblock amides (PEBAX), polyethylene terephthalate (PET), silicone, POC,polypropylene, polyether block PBT and the like. The balloon 38 mayinclude multiple layers and/or be coextruded and may also includeadditional fiber reinforcements.

The pair of balloons 38 a, 38 b may be inflated simultaneously byinjecting gas or liquid such as air or saline into the balloon inflationport 34 at the proximal end 17 of the catheter 12 and through theballoon inflation tube 36 extending longitudinally with the catheter 12.The balloon inflation tube 36 may be integrated with the catheter 12,for example, molded within the walls of the catheter 12, bonded to thecatheter 12, or separate from the catheter 12. It may be desired toinclude a separate balloon inflation tube 36 from the inner lumen 52 toindependently control inflation or deflation of the balloons 38 a, 38 bwhile also using the inner lumen 52 as a fluid channel for the deliveryof viral vectors 18. In this respect gas or liquid may flow through aballoon lumen that is separate from the inner lumen 52 of the catheter12. Alternatively, the gas or liquid may flow through the same tube asthe inner lumen 52 of the catheter 12

The balloon 38 may be constructed as described above and as described inU.S. Pat. Nos. 8,603,064 and 7,060,051, both of which are herebyincorporated by reference.

The balloons 38 a, 38 b may secure the positioning of the catheter 12within the lower blood vessel 42 by engaging the inner walls of thelower blood vessel 42 thus anchoring the catheter 12 to the lower bloodvessel 42 when inflated, and then deflated for removal of the catheter12 from the lower blood vessel 42 and from the body.

The balloons 38 a, 38 b also provide additional benefit by localizingthe dispersion of the viral vectors 18 to a gene delivery area 64substantially longitudinally bounded by the pair of inflated balloons 38a, 38 b. In this respect, when viral vector 18 is injected into theinner lumen 52 of the catheter 12, the inflated balloons 38 a, 38 bprevent the viral vector 18 from flowing downstream or upstream throughthe lower blood vessel 42. Therefore, the viral vectors 18 areencouraged to be absorbed into the nearby surrounding hepatic tissue, ormay flow into smaller lateral vessels and capillaries to then beabsorbed into the nearby surrounding hepatic tissue, instead ofreturning up the vein toward the proximal port 30 or down the vein fromthe terminal end 54 of the catheter 12.

The inflated balloons 38 a, 38 b also block blood flow between theinflated balloons 38 during gene delivery.

Referring to FIGS. 3 and 4, each catheter 12 may support an antennaproviding an electrical conductor 70, extending coaxially within theinternal lumen 52 along the longitudinal axis 62 of the catheter 12. Theinternal electrical conductor 70 may also be coaxially positioned withinthe internal lumen 52 so that it does not block or obscure any of theexit ports 58, for example, it may be substantially centered within thelumen 52. The outer dimension of the internal electrical conductor 70 isless than the inner diameter of the outer wall 50 of the catheter 12 toprovide clearance around the internal electrical conductor 70 for viralvector 18 to fill in and flow though and out. The internal electricalconductor 70 may extend substantially an entire length of the catheter12, however, terminating before reaching the terminal end 54 of thecatheter 12, or before the distal balloon 38 b. The internal electricalconductor 70 is configured to carry electrical charge and may be copperplated steel or stainless steel with or without an outer dielectricinsulator permitting free passage of the electrical field but blockingelectrical current flow and chemical reaction between the fluid and thematerial of the electrical conductor 70.

The internal electrical conductor 70 may be shielded above the activesection 60, or above the proximal balloon 38 a, by an insulator 72layer, an outer conductor 73 layer, and an insulator shield or jacket75. The outer conductor 73 layer may be connected to a ground potentialwhile the internal electrical conductor 70 is connected to a powersource. In this respect, the electric field is restricted to thedielectric and does not extend from the shielded section 74. Forexample, a shielded portion 74 may be a shielded cable, such as acoaxial cable, or a layered medical tubing with the internal electricalconductor 70 surrounded by a tubular insulating layer 72, for example, asolid plastic or a foam plastic such as solid polytetrafluoroethylene(PTFE) or solid polyethylene (PE) dielectric, and further surrounded bya tubular outer conductor 73, for example, a metal braided shield suchas braided copper, aluminum or stainless steel wire, which may be platedor multi-layered, and may be further surrounded by an insulating shieldor jacket 75, for example, a solid plastic such as polyvinyl chloride(PVC) which may be sealed around the outer conductor 73 to preventreaction with fluids and the like.

The internal electrical conductor 70 may extend into the active section60 with the insulator 72, outer conductor 73, and insulator jacket 75removed. In this respect, the electric fields in the shielded portion 74above the active section 60 are reduced and do not extend into thesurrounding hepatic tissue 44 until reaching the active section 60 ofthe catheter 12. Alternatively, the internal electrical conductor 70 mayremain insulated in the active section 60 with only the outer conductor73 and insulator jacket 75 removed. In this respect, electrical currentis blocked from flowing into the surrounding hepatic tissue 44 and theinternal electrical conductor 70 is not exposed to chemical reactionwith the hepatic tissue 44. It is understood that the shielded portion74 may still have an outer dimension less than the inner diameter of theouter wall 50 of the catheter 12 to provide clearance therearound forflow of viral vector 18.

Referring also to FIG. 5, the internal electrical conductors 70 a, 70 bof each catheter 12 a, 12 b may be used in conjunction with a pulsegenerator 76 providing a pulsed electrical charge to the internalelectrical conductors 70 a, 70 b. For example, the pulse generator 76may deliver a direct current (DC) in the form of a repeated pulse orburst of an appropriate current amplitude and duration to one of theinternal electrical conductors 70 a, 70 b to create a voltage (i.e.,potential difference) between the internal electrical conductors 70 a,70 b. An electric pulse may be applied to one of the internal electricalconductors 70 a, 70 b receiving positive direct current while the otherof the internal electrical conductors 70 a, 70 b acts as the return,negatively biased electrode. The shield or outer conductor 73 isgrounded halfway between the two potential biases.

Pulse generators 76 suitable for in vivo electroporation as taughtherein are sold by ECM under the trade name “830 square waveelectroporation system”. Other pulse generators 76 are also commerciallyavailable and may be used with the present invention.

As illustrated in FIG. 5, the electric pulses may be repeated squarepulses created by the pulse generator 76. It is understood that theelectric pulses may take other shapes such as spikes or round waves. Anelectronic control circuit 78 may communicate with the pulse generator76 to receive a preset voltage output and pulse length from the medicalprofessional. The electronic control circuit 78 may hold, for example, amicroprocessor 80 for executing a program 82 held in a stored memory 84.

The microprocessor 80 may also receive input data from the medicalprofessional such as a distance between internal electrical conductors70 a, 70 b, or a cross-sectional area between internal electricalconductors 70 a, 70 b, and execute the program 82 held in the storedmemory 84 to output a voltage output 86 and pulse duration 88 to be usedfor effective pulse delivery, for example, using a lookup table.

It is understood that internal electrical conductors 70 a, 70 b may beangled with respect to each other and may not be perfectly parallelalong the active section 60. In this manner, the medical professionalmay take the largest distance or area therebetween or take an averagedistance or area therebetween in determining the distance betweeninternal electrical conductors 70 a, 70 b and an effective pulsedelivery.

The voltage output 86 may be selected so that the electric field 46created between the internal electrical conductors 70 a, 70 b achievesor exceeds an efficacious electric field strength. For example, if theelectric field 46 is too high, this can result in cell death throughirreversible electroporation. Alternatively, if the electric fieldstrength is too low, the transmembrane potential required topermeabilize the cell membrane (typically 0.7 V) cannot be reached.

The pulse duration 88 may also be selected so that the electric field 46created between the internal electrical conductors 70 a, 70 b achievesor exceeds an efficacious electric field 46 strength. For example, ifthe pulse length is too short, (microseconds), the membrane capacitancemay not charge up high enough to reach the required transmembranepotential. An efficacious electric field 46 strength may be coextensivewith the gene delivery area 64.

It has found that for gene delivery (compared to drug delivery), acombination of low electric field strength and long pulse length hasbeen effective. For example, electric field intensities between 100-200V/cm and pulse durations of 38-100 msec; and electric field intensitiesbetween 200-275 V/cm and pulse duration of about 50 msec have been foundto be effective. Other parameters, which determine the efficacy of thedelivery of viral vectors 18 into hepatic cells 44 are field strength,pulse length, shape of the pulse and number of pulses.

The parameters of the electroporation described above may be as furtherdescribed in Methods in Molecular Medicine, Vol. 37: ElectricallyMediated Delivery of Molecules to Cells, Edited by: M. J. Jaroszeski, R.Heeller, and R. Gilbert, Humana Press, Inc., Totowa, N J, and herebyincorporated by reference.

Referring now to FIG. 6, as noted above, the present invention uses apair of catheters 12 a, 12 b to provide more efficient gene deliveryeliminating the need for large vector doses or a highly invasiveprocedure. Such a procedure can use a pair of minimally invasivevascular catheters 12 a, 12 b catheterizing lower blood vessels 42 a, 42b of the liver 24 to perform direct gene delivery into the target liverwith greater efficacy. To further enhance the efficiency of genedelivery for a large tissue area, the catheters 12 a, 12 bsimultaneously electroporate the hepatic cells 44 between adjacentelectrodes to open temporary pores in the cell membrane allowing thevector 18 to readily enter the cells.

As indicated by process block 100, a first catheter 12 a may be insertedthrough a venous access site 20, for example, the jugular vein 20 b,through a small incision at the neck of the human patient 14. Themedical professional may use a guidewire and/or real-time visual imagingsuch as ultrasound or x-ray (fluoroscopy) to assist with thecatheterization of the hepatic vein 22. A second catheter 12 b may besimilarly inserted through the venous access site 20 to catheterize thehepatic vein 22.

As indicated by process block 102, once the catheters 12 a, 12 b areproperly positioned within adjacent, coextending lower blood vessels 42a, 42 b of the liver 24, the respective balloons 38 a, 38 b may beinflated by injecting gas or fluid such as air or saline through theballoon inflation port 34 and through the inflation tube 36 in order tosecure the catheters 12 a, 12 b in position, prevent further blood flowbetween the balloons 38 a, 38 b, and to isolate the gene delivery area64. The balloons 38 a, 38 b of each catheter 12 a, 12 b may inflatesimultaneously and to a similar extent such that the inflated balloons38 a, 38 b of each respective catheter 12 a, 12 b are a similar size. Inthis respect the balloons 38 a, 38 b of the catheter 12 a may be adifferent size from the balloons 38 a, 38 b of the catheter 12 b toaccommodate for different inner diameter sizes of the blood vessels 42a, 42 b.

Optionally, saline may be injected into the proximal ports 30 of thecatheters 12 a, 12 b to wash the inner lumen 52 and gene delivery area64 from obstructive blood and tissues.

Then, as indicated by process block 104, the viral vector 18 may beinjected into the proximal ports 30 of the catheters 12 a, 12 b in orderto fill the inner lumen 52 of the catheters 12 a, 12 b with the viralvector 18 and to disseminate the vector 18 through the exit ports 56 ofthe outer wall 50 of the catheters 12 a, 12 b, and further through thevascular walls of the lower blood vessels 42 a, 42 b, and into the genedelivery area 64 surrounding the catheters 12 a, 12 b. It is understoodthat the gene delivery area 64 may comprise of regions emanating fromand surrounding the active section 60 of each catheter 12 a, 12 b.

As indicated by process block 106, the medical professional may considerthe location and distance between the catheters 12 a, 12 b using visualimaging such as ultrasound or x-ray to determine a desired voltageoutput 86 and pulse duration 88 to be outputted by the pulse generator76. The medical professional may program the pulse generator 76 toelicit a direct current in short pulses, for example, square waves asillustrated in FIG. 5, to the internal electrical conductors 70 of thecatheters 12 a, 12 b to therefore create an electric field 46surrounding the catheters 12 a, 12 b. It is understood that the electricfield 46 may comprise of a region surrounding the catheters 12 a, 12 band extending across the catheters 12 a, 12 b, the tissue areacoextensive or greater than the gene delivery area 64.

The electroporation of the gene delivery area 64 provided by theelectric field 46 allows for the hepatic cells 44 in the gene deliveryarea 64 to be more susceptible to viral intake. In this respect, thecatheters 12 allow for simultaneous or nearly simultaneous delivery ofgenes to cells with electroporation of the cells extending between thepair of catheters 12. It is contemplated that the drug deliverydescribed above may be performed once or may be conducted as repeatedtreatments as necessary.

It is understood that the gene therapy delivery system 10 may beperformed on any mammal and of any size, for example, both small andlarge mammals.

Certain terminology is used herein for purposes of reference only, andthus is not intended to be limiting. For example, terms such as “upper”,“lower”, “above”, and “below” refer to directions in the drawings towhich reference is made. Terms such as “front”, “back”, “rear”, “bottom”and “side”, describe the orientation of portions of the component withina consistent but arbitrary frame of reference which is made clear byreference to the text and the associated drawings describing thecomponent under discussion. Such terminology may include the wordsspecifically mentioned above, derivatives thereof, and words of similarimport. Similarly, the terms “first”, “second” and other such numericalterms referring to structures do not imply a sequence or order unlessclearly indicated by the context.

When introducing elements or features of the present disclosure and theexemplary embodiments, the articles “a”, “an”, “the” and “said” areintended to mean that there are one or more of such elements orfeatures. The terms “comprising”, “including” and “having” are intendedto be inclusive and mean that there may be additional elements orfeatures other than those specifically noted. It is further to beunderstood that the method steps, processes, and operations describedherein are not to be construed as necessarily requiring theirperformance in the particular order discussed or illustrated, unlessspecifically identified as an order of performance. It is also to beunderstood that additional or alternative steps may be employed.

References to “a microprocessor” and “a processor” or “themicroprocessor” and “the processor,” can be understood to include one ormore microprocessors that can communicate in a stand-alone and/or adistributed environment(s), and can thus be configured to communicatevia wired or wireless communications with other processors, where suchone or more processor can be configured to operate on one or moreprocessor-controlled devices that can be similar or different devices.Furthermore, references to memory, unless otherwise specified, caninclude one or more processor-readable and accessible memory elementsand/or components that can be internal to the processor-controlleddevice, external to the processor-controlled device, and can be accessedvia a wired or wireless network.

It is specifically intended that the present invention not be limited tothe embodiments and illustrations contained herein and the claims shouldbe understood to include modified forms of those embodiments includingportions of the embodiments and combinations of elements of differentembodiments as come within the scope of the following claims. All of thepublications described herein, including patents and non-patentpublications, are hereby incorporated herein by reference in theirentireties.

What we claim is:
 1. A gene therapy delivery system comprising: a firstballoon catheter providing a distal end having a first and secondinflatable balloon spaced apart along the distal end to define anintervening catheter section and at least one passageway through adelivery lumen of the intervening catheter section for the delivery of agene vector; a second balloon catheter providing a distal end having afirst and second inflatable balloon spaced apart along the distal end todefine an intervening catheter section and at least one passagewaythrough a delivery lumen of the intervening catheter section for thedelivery of a gene vector; a first electrode extending along the firstballoon catheter; a second electrode extending along the second ballooncatheter; and a power supply providing a voltage across the first andsecond balloon catheters.
 2. The system of claim 1 wherein the first andsecond electrode extend within the delivery lumen of the first andsecond balloon catheter, respectively.
 3. The system of claim 1 whereinthe first and second electrode terminate before a distal tip of thefirst and second balloon catheters, respectively.
 4. The system of claim1 wherein the first and second electrode extend substantially parallelwith a catheter sidewall.
 5. The system of claim 1 wherein the first andsecond electrode provides a coaxial conductor having an inner and anouter coaxial conductive element and wherein the outer conductiveelement is removed from the coaxial conductor within the interveningcatheter section to allow transmission of electrical field forelectroporation.
 6. The system of claim 5 wherein a proximal end of thecatheter provides an electrical connector providing separate connectionsto the inner and outer coaxial conductive elements.
 7. The system ofclaim 5 wherein the inner conductive element is stainless steel.
 8. Thesystem of claim 5 wherein the first and second electrode provides acoaxial conductor wherein the coaxial conductor is insulated within theintervening catheter section to prevent current flow to an exterior ofthe first and second balloon catheters.
 9. The system of claim 1 whereinthe intervening catheter section includes a plurality of perfusion holesspaced along the intervening catheter section.
 10. The system of claim 1wherein the intervening catheter section includes at least one perfusionhole centered within the intervening catheter section.
 11. The system ofclaim 1 wherein one of the first and second inflatable balloon ispositioned at a distal tip of the first and second balloon catheters.12. The system of claim 1 wherein the catheter has at least two lumens,one communicating with at least one of the balloon catheters and theother communicating with the delivery lumen.
 13. A method of genetherapy comprising: providing a first balloon catheter providing adistal end having a first and second inflatable balloon spaced apartalong the distal end to define an intervening catheter section and atleast one passageway through a delivery lumen of the interveningcatheter section for the delivery of a gene vector, a first electrodeextending along the first balloon catheter; providing a second ballooncatheter providing a distal end having a first and second inflatableballoon spaced apart along the distal end to define an interveningcatheter section and at least one passageway through a delivery lumen ofthe intervening catheter section for the delivery of a gene vector, asecond electrode extending along the second balloon catheter; insertingthe first balloon catheter into a first blood vessel of a patient;inserting the second balloon catheter into a second blood vessel of thepatient; injecting a gene vector through the delivery lumen of theintervening catheter section to deliver the gene vector into surroundingcells; and delivering an electrical charge to one of the first andsecond electrodes to produce a voltage across between the first andsecond balloon catheter.
 14. The method of claim 13 wherein the firstand second electrical conductor electrodes are separated by an averagedistance of 5-30 mm.
 15. The method of claim 13 wherein one of the firstand second electrodes receives the electrical charge and the other is areturn electrode.